Let's suppose that I have the following code:

const id = '1'

const arrayOfIds = ['1', '2', '3']

And I want to check if id is in arrayOfIds

Something like this

expect(id).toBeIn(arrayOfIds)

How can I do this with Jest?

Let's suppose that I have the following code:

const id = '1'

const arrayOfIds = ['1', '2', '3']

And I want to check if id is in arrayOfIds

Something like this

expect(id).toBeIn(arrayOfIds)

How can I do this with Jest?

• javascript
• jestjs

• 1 Would expect(arrayOfIds.includes(id)).toBe(true) work? – evolutionxbox Commented Feb 3, 2021 at 17:21
• No, must be the contrary – Rodrigo Commented Feb 3, 2021 at 17:25
• 1 So, toBe(false)? But you asked "check if id is in arrayOfIds"? – evolutionxbox Commented Feb 3, 2021 at 17:27

2 Answers 2

Use .toContain when you want to check that an item is in an array. For testing the items in the array, this uses ===, a strict equality check.

test('is id in arrayOfIds', () => {
        const id = '1';
        const arrayOfIds = ['1', '2', '3'];
        expect(arrayOfIds).toContain(id);
});

    expect(['a', 2, '3']).toContain(2);
    expect(['a', 2, '3']).toContain('3');